Resist underlayer film forming composition for lithography containing polyether structure-containing resin

ABSTRACT

There is provided a resist underlayer film forming composition for forming a resist underlayer film providing heat resistance properties and hardmask characteristics. A resist underlayer film forming composition for lithography, comprising: a polymer containing a unit structure of Formula (1): 
       O—Ar 1   Formula (1)
 
     (in Formula (1), Ar 1  is a C 6-50  arylene group or an organic group containing a heterocyclic group), a unit structure of Formula (2): 
       O—Ar 2 —O—Ar 3 -T-Ar 4   Formula (2)
 
     (in Formula (2), Ar 2 , Ar 3 , and Ar 4  are individually a C 6-50  arylene group or an organic group containing a heterocyclic group; and T is a carbonyl group or a sulfonyl group), or a combination of the unit structure of Formula (1) and the unit structure of Formula (2). The organic groups of Ar 1  and Ar 2  containing arylene group may be organic groups containing a fluorene structure.

TECHNICAL FIELD

The present invention relates to a resist underlayer film formingcomposition for lithography that is effectively used for processing of asemiconductor substrate, a resist pattern forming method employing theresist underlayer film forming composition, and a method for producing asemiconductor device.

BACKGROUND ART

Conventionally, in the production of semiconductor devices, fineprocessing by lithography using a photoresist composition has beenperformed. The fine processing is a processing method including: forminga thin film of a photoresist composition on a substrate to be processedsuch as a silicon wafer; irradiating the resultant thin film with anactive ray such as an ultraviolet ray through a mask pattern in which apattern of a semiconductor device is depicted for development; andetching the substrate to be processed such as a silicon wafer using theresultant photoresist pattern as a protecting film. Recently, however,the high integration of semiconductor devices has progressed and theadopted active ray tends to have a shorter wavelength, such as an ArFexcimer laser (193 nm) replacing a KrF excimer laser (248 nm). Followingsuch a tendency, the influence of diffused reflection of an active rayon a substrate or a standing wave has become a large problem. To addressthis, what has been widely studied is the use of an anti-reflectivecoating (Bottom Anti-Reflective Coating, BARC) between the photoresistand the substrate to be processed.

Progress in refinement of the resist pattern will cause a problem of theresolution or collapse of a resist pattern after development; therefore,thinning of the resist will be required. In this sense, it is difficultto secure a resist pattern film thickness sufficient for processing thesubstrate, which requires a process for imparting a function as a maskfor processing the substrate not only to the resist pattern, but also tothe resist underlayer film provided between the resist and thesemiconductor substrate to be processed. As a resist underlayer film forsuch a process, there have started to be required a resist underlayerfilm for lithography having a selection ratio of a dry etching rateclose to that of the resist, a resist underlayer film for lithographyhaving a selection ratio of a dry etching rate smaller than that of theresist, and a resist underlayer film for lithography having a selectionratio of a dry etching rate smaller than that of the semiconductorsubstrate, as a resist underlayer film, unlike a conventional resistunderlayer film having high etching rate property (high etching rate).

In addition, a heat resistant resist underlayer film having a fluorenestructure is disclosed (Patent Document 1).

PRIOR-ART DOCUMENT Patent Document

Patent Document 1: International Publication No. WO 2010/041626 pamphlet

SUMMARY OF THE INVENTION Problem to be Solved by the Invention

The present invention provides a resist underlayer film formingcomposition for using for a lithography process of the production ofsemiconductor devices. It is an object of the present invention toprovide a resist underlayer film for lithography causing no intermixingwith a resist layer, providing an excellent resist pattern, and having:a selection ratio of a dry etching rate close to that of the resist; aselection ratio of a dry etching rate smaller than that of the resist;or a selection ratio of a dry etching rate smaller than that of thesemiconductor substrate. The present invention also provides a resistunderlayer film for lithography capable of imparting performance ofeffectively absorbing light reflected on the substrate when irradiatedlight having a wavelength of 248 nm, 193 nm, 157 nm, or the like is usedfor fine processing. Furthermore, it is an object of the presentinvention to provide a resist pattern forming method using the resistunderlayer film forming composition. Then, the present inventionprovides a resist underlayer film forming composition for forming aresist underlayer film providing heat resistance in combination withother advantageous properties.

Means for Solving the Problem

The present invention is, according to a first aspect, a resistunderlayer film forming composition for lithography, containing apolymer containing a unit structure of Formula (1):

O—Ar₁  Formula (1)

(in Formula (1), Ar₁ is a C₆₋₅₀ arylene group or an organic groupcontaining a heterocyclic group), a unit structure of Formula (2):

O—Ar₂—O—Ar₃-T-Ar₄  Formula (2)

(in Formula (2), Ar₂, Ar₃, and Ar₄ are individually a C₆₋₅₀ arylenegroup or an organic group containing a heterocyclic group; and T is acarbonyl group or a sulfonyl group), or a combination of the unitstructure of Formula (1) and the unit structure of Formula (2),

according to a second aspect, the resist underlayer film formingcomposition according to the first aspect, in which the resistunderlayer film forming composition for lithography contains a polymercontaining the unit structure of Formula (1), and the organic group ofAr₁ is an organic group containing a fluorene structure,

according to a third aspect, the resist underlayer film formingcomposition according to the first aspect, in which the resistunderlayer film forming composition for lithography contains a polymercontaining the unit structure of Formula (2), and the organic group ofAr₂ is an organic group containing a fluorene structure,

according to a fourth aspect, the resist underlayer film formingcomposition according to the first aspect, in which the resistunderlayer film forming composition for lithography contains a polymercontaining a combination of the unit structure of Formula (1) and theunit structure of Formula (2), and at least one of the organic group ofAr₁ and the organic group of Ar₂ is an organic group containing afluorene structure,

according to a fifth aspect, the resist underlayer film formingcomposition according to the first aspect, in which the resistunderlayer film forming composition for lithography contains a polymercontaining the unit structure of Formula (1), and the organic group ofAr₁ is an organic group containing a combination of an arylene groupwith a group containing a carbon-carbon triple bond and/or a groupcontaining a carbon-carbon double bond,

according to a sixth aspect, the resist underlayer film formingcomposition according to the first aspect, in which the resistunderlayer film forming composition for lithography contains a polymercontaining the unit structure of Formula (2), and the organic group ofAr₂ is an organic group containing a combination of an arylene groupwith a group containing a carbon-carbon triple bond and/or a groupcontaining a carbon-carbon double bond,

according to a seventh aspect, the resist underlayer film formingcomposition according to the first aspect, in which the resistunderlayer film forming composition for lithography contains a polymercontaining a combination of the unit structure of Formula (1) and theunit structure of Formula (2), and at least one of the organic group ofAr₁ and the organic group of Ar₂ is an organic group containing acombination of an arylene group with a group containing a carbon-carbontriple bond and/or a group containing a carbon-carbon double bond,

according to an eighth aspect, the resist underlayer film formingcomposition according to the first aspect, in which the resistunderlayer film forming composition for lithography contains a polymercontaining the unit structure of Formula (1), and the organic group ofAr₁ is an organic group containing a biphenylene structure,

according to a ninth aspect, the resist underlayer film formingcomposition according to the first aspect, in which the resistunderlayer film forming composition for lithography contains a polymercontaining the unit structure of Formula (2), and the organic group ofAr₂ is an organic group containing a biphenylene structure,

according to a tenth aspect, the resist underlayer film formingcomposition according to the first aspect, in which the resistunderlayer film forming composition for lithography contains a polymercontaining a combination of the unit structure of Formula (1) and theunit structure of Formula (2), and at least one of the organic group ofAr₁ and the organic group of Ar₂ is an organic group containing abiphenylene structure,

according to an eleventh aspect, the resist underlayer film formingcomposition according to the first aspect, in which the resistunderlayer film forming composition for lithography contains a polymercontaining the unit structure of Formula (2), and at least one of theorganic group of Ar₃ and the organic group of Ar₄ is a phenylene group,

according to a twelfth aspect, the resist underlayer film formingcomposition according to the first aspect, in which the resistunderlayer film forming composition for lithography contains a polymercontaining a combination of the unit structure of Formula (1) and theunit structure of Formula (2), and at least one of the organic group ofAr₃ and the organic group of Ar₄ is a phenylene group,

according to a thirteenth aspect, the resist underlayer film formingcomposition according to any one of the first aspect to the twelfthaspect further containing an acid or an acid generator,

according to a fourteenth aspect, a resist underlayer film obtained byapplying the resist underlayer film forming composition described in anyone of the first aspect to the thirteenth aspect onto a semiconductorsubstrate and baking the resultant film,

according to a fifteenth aspect, a method for producing a semiconductordevice including: a process of forming an underlayer film with theresist underlayer film forming composition described in any one of thefirst aspect to the thirteenth aspect on a semiconductor substrate; aprocess of forming a resist film on the underlayer film; a process ofirradiating the resist film with light or an electron beam anddeveloping the resist film so as to form a resist pattern; a process ofetching the underlayer film according to the resist pattern of theresist film; and a process of processing the semiconductor substrateaccording to the patterned underlayer film, and

according to a sixteenth aspect, a method for producing a semiconductordevice including: a process of forming an underlayer film with theresist underlayer film forming composition described in any one of thefirst aspect to the thirteenth aspect on a semiconductor substrate; aprocess of forming a hardmask on the underlayer film; a process offurther forming a resist film on the hardmask; a process of irradiatingthe resist film with light or an electron beam and developing the resistfilm so as to form a resist pattern; a process of etching the hardmaskaccording to the resist pattern of the resist film; a process of etchingthe underlayer film according to the patterned hardmask; and a processof processing the semiconductor substrate according to the patternedunderlayer film.

Effect of the Invention

With the resist underlayer film forming composition of the presentinvention, an advantageous pattern shape of a resist can be formedwithout causing intermixing with an upper layer of the resist underlayerfilm.

The resist underlayer film forming composition of the present inventioncan have performance of effectively suppressing reflection on thesubstrate and provide an effect as an anti-reflective coating forexposure light in combination with other advantageous properties.

The resist underlayer film forming composition of the present inventioncan provide an excellent resist underlayer film having a selection ratioof a dry etching rate close to that of the resist, a selection ratio ofa dry etching rate smaller than that of the resist, or a selection ratioof a dry etching rate smaller than that of the semiconductor substrate.

Due to refinement of the resist pattern, for preventing the resistpattern from collapsing after development, thinning of the resist isperformed. For such a thin film resist, there is a process including:transferring a resist pattern to an underlayer film thereof by etchingprocess; and processing the substrate using the underlayer film as amask. There is another process in which a process including transferringa resist pattern to an underlayer film thereof by etching process andfurther transferring the pattern transferred to the underlayer film toan underlayer film thereof using a gas having a different gascomposition is repeatedly performed so that the substrate is processed.The resist underlayer film and the forming composition thereof of thepresent invention are effective for these processes and when thesubstrate is processed using the resist underlayer film of the presentinvention, the resist underlayer film has satisfactory etchingresistance relative to the substrate to be processed (for example, athermally oxidized silicon film, a nitride silicon film, a polysiliconfilm, and the like on the substrate).

The resist underlayer film of the present invention can be used as aplanarization film, a resist underlayer film, a contamination preventingfilm for the resist layer, and a film having dry etching selectivity.Use of the resist underlayer film of the present invention makes itpossible to easily and accurately perform the formation of a resistpattern in a lithography process of the semiconductor production.

There is a process including: forming a resist underlayer film with aresist underlayer film forming composition on a substrate; forming ahardmask on the resist underlayer film; forming a resist film on thehardmask; forming a resist pattern by exposure and development;transferring the resist pattern to the hardmask; transferring the resistpattern transferred to the hardmask to the resist underlayer film; andprocessing the semiconductor substrate according to the resistunderlayer film. In this process, there are a case where the formationof the hardmask is performed by a coating-type composition containing anorganic polymer or an inorganic polymer and a solvent, and a case wherethe formation of the hardmask is performed by vacuum deposition of aninorganic substance. In vacuum deposition of an inorganic substance (forexample, silicon nitride oxide), a deposited substance is deposited onthe surface of the resist underlayer film and at this time, thetemperature of the surface of the resist underlayer film is elevated toaround 400° C. In the resist underlayer film forming composition of thepresent invention, the used polymer is a copolymer containing apolyether structure, for example, a unit structure of fluorene naphtholand a unit structure of arylene alkylene, so that the used polymer hasextremely high heat resistance and is difficult to cause thermaldegradation even by the deposition of the deposited substance.

BEST MODES FOR CARRYING OUT THE INVENTION

The present invention is a resist underlayer film forming compositionfor lithography containing a polymer containing a unit structure ofFormula (1), a unit structure of Formula (2), or a unit structurecontaining a combination of these unit structures.

The resist underlayer film forming composition may contain acrosslinking agent, an acid, and if necessary, an additive such as anacid generator and a surfactant. The solid content of the composition is0.1 to 70% by mass or 0.1 to 60% by mass. The solid content is a contentof a component remaining after a solvent is removed from the resistunderlayer film forming composition.

In the solid content, the above polymer can be contained in a content of1 to 100% by mass, 1 to 99% by mass, or 50 to 99% by mass.

The polymer used in the present invention has a weight average molecularweight of 600 to 1,000,000, preferably 1,000 to 200,000.

The unit structure of Formula (1) is a unit structure having a polyetherstructure and the unit structure of Formula (2) is a unit structurehaving a polyetheretherketone structure or a polyetherethersulfonstructure.

In the unit structure of Formula (1), Ar₁ is a C₆₋₅₀ arylene group or anorganic group containing a heterocyclic group. The organic group is, forexample, a divalent to tetravalent group. In Formula (2), Ar₂, Ar₃, andAr₄ are individually a C₆₋₅₀ arylene group or an organic groupcontaining a heterocyclic group, and T is a carbonyl group or a sulfonylgroup. Arylene groups or heterocyclic groups in the organic groups ofAr₁ to Ar₄ can be used individually or in combination of two or more ofthem. The arylene group and the heterocyclic group are, for example, adivalent to tetravalent group.

The C₆₋₅₀ arylene group is a divalent organic group corresponding to anaryl group and examples thereof include divalent groups corresponding toa phenyl group, an o-methylphenyl group, a m-methylphenyl group, ap-methylphenyl group, an o-chlorophenyl group, a m-chlorophenyl group, ap-chlorophenyl group, an o-fluorophenyl group, a p-fluorophenyl group,an o-methoxyphenyl group, a p-methoxyphenyl group, a p-nitrophenylgroup, a p-cyanophenyl group, an α-naphthyl group, a β-naphthyl group,an o-biphenylyl group, a m-biphenylyl group, a p-biphenylyl group, a1-anthryl group, a 2-anthryl group, a 9-anthryl group, a 1-phenanthrylgroup, a 2-phenanthryl group, a 3-phenanthryl group, a 4-phenanthrylgroup, a 9-phenanthryl group, a fluorene group, a fluorene derivativegroup, a pyrene group, and a pentacene group.

Examples of the heterocyclic group include organic groups correspondingto heterocyclic rings such as pyrrole, thiophene, furan, imidazole,triazole, oxazole, thiazole, pyrazole, isoxazole, isothiazole, pyridine,pyridazine, pyrimidine, pyrazine, piperidine, piperazine, morpholine,pyran, and carbazole.

The organic group containing a C₆₋₅₀ arylene group can be used as theabove arylene group alone or as a combination of the above arylene groupwith a group containing a carbon-carbon triple bond and/or a groupcontaining a carbon-carbon double bond.

Examples of the organic group containing the above arylene group includean organic group containing a fluorene structure or an organic groupcontaining a biphenylene structure.

The unit structure of the polymer used in the present invention can beexemplified as follows.

The resist underlayer film forming composition of the present inventionmay contain a crosslinking agent component. Examples of the crosslinkingagent include a melamine-based crosslinking agent, a substitutedurea-based crosslinking agent, and a polymer thereof-based crosslinkingagent. The crosslinking agent is preferably a crosslinking agent havingat least two crosslinkage forming substituents and examples thereofinclude compounds such as methoxymethylated glycoluril, butoxymethylatedglycoluril, methoxymethylated melamine, butoxymethylated melamine,methoxymethylated benzoguanamine, butoxymethylated benzoguanamine,methoxymethylated urea, butoxymethylated urea, methoxymethylatedthiourea, and methoxymethylated thiourea. A condensation product ofthese compounds can also be used.

As the crosslinking agent, a crosslinking agent having high heatresistance can be used. As the crosslinking agent having high heatresistance, a compound containing, in the molecule thereof, acrosslinkage forming substituent having an aromatic ring (such as abenzene ring and a naphthalene ring) can be preferably used.

Examples of such a compound include a compound having a partialstructure of Formula (4) below, a polymer or an oligomer having arepeating unit of Formula (5) below.

In Formula (4), R₇ and R₈ are individually a hydrogen atom, a C₁₋₁₀alkyl group, or a C₆₋₂₀ aryl group; and n7 is an integer of 1 to 4, n8is an integer of 1 to (5−n7) and n7+n8 is an integer of 2 to 5. InFormula (5), R₉ is a hydrogen atom or a C₁₋₁₀ alkyl group; R₁₀ is aC₁₋₁₀ alkyl group; and n9 is an integer of 1 to 4, n10 is an integer of0 to (4−n9) and n9+n10 is an integer of 1 to 4. The polymer and theoligomer can be used in a range of the number of repeating unitstructures of 2 to 100 or 2 to 50. Examples of the alkyl group and thearyl group include individually the above examples.

The compound of Formula (4), the polymer, oligomer thereof and thecompound of Formula (5), the polymer and oligomer thereof areexemplified as follows.

The above compounds are commercially available as the products of AsahiOrganic Chemicals Industry Co., Ltd. and Honshu Chemical Industry Co.,Ltd. For example, among the above crosslinking agents, a compound ofFormula (6-21) is commercially available from Asahi Organic ChemicalsIndustry Co., Ltd. under a trade name: TM-BIP-A.

Although the additive amount of the crosslinking agent is varieddepending on the used coating solvent, the used ground substrate, therequired viscosity of solution, the required film shape, and the like,it is 0.001 to 80% by mass, preferably 0.01 to 50% by mass, furtherpreferably 0.05 to 40% by mass, based on the total mass of the solidcontent. Although the crosslinking agent may effect a crosslinkingreaction by self-condensation, when a crosslinkable substituent existsin the above polymer of the present invention, the crosslinking agentcan effect the crosslinking reaction with such a crosslinkablesubstituent.

In the present invention, as a catalyst for accelerating thecrosslinking reaction, an acidic compound such as p-toluenesulfonicacid, trifluoromethanesulfonic acid, pyridinium-p-toluenesulfonic acid,salicylic acid, sulfosalicylic acid, citric acid, benzoic acid,hydroxybenzoic acid, and naphthalenecarboxylic acid or/and a thermoacidgenerator such as 2,4,4,6-tetrabromocyclohexadienone, benzoin tosylate,2-nitrobenzyl tosylate, and organic sulfonic acid alkyl esters can beblended. The blending amount thereof is 0.0001 to 20% by mass,preferably 0.0005 to 10% by mass, more preferably 0.01 to 3% by mass,based on the total mass of the solid content.

In the coating-type underlayer film forming composition for lithographyof the present invention, for conforming the acidity of the underlayerfilm forming composition to the acidity of the photoresist applied as anupper layer of the underlayer film thereon in a lithography process, aphotoacid generator can be blended. Preferred examples of the photoacidgenerator include: onium salt photoacid generators such asbis(4-tert-butylphenyl)iodonium trifluoromethanesulfonate andtriphenylsulfonium trifluoromethanesulfonate; halogen-containingcompound photoacid generators such asphenyl-bis(trichloromethyl)-s-triazine; and sulfonic acid-basedphotoacid generators such as benzoin tosylate and N-hydroxysuccinimidetrifluoromethanesulfonate. The content of the photoacid generator is 0.2to 10% by mass, preferably 0.4 to 5% by mass, based on the total mass ofthe solid content.

In the resist underlayer film material for lithography of the presentinvention, besides the above components, if necessary, an additionallight absorber, a rheology controlling agent, an adhesion assistant, asurfactant, and the like can be added.

As the additional light absorber, there can be preferably used, forexample, commercially available light absorbers described in “Technologyand market of industrial dyestuff” (published by CMC Publishing CO.,Ltd.) or “Dye handbook” (published by the Society of Synthetic OrganicChemistry, Japan) such as C. I. Disperse Yellow 1, 3, 4, 5, 7, 8, 13,23, 31, 49, 50, 51, 54, 60, 64, 66, 68, 79, 82, 88, 90, 93, 102, 114,and 124; C. I. Disperse Orange 1, 5, 13, 25, 29, 30, 31, 44, 57, 72, and73; C. I. Disperse Red 1, 5, 7, 13, 17, 19, 43, 50, 54, 58, 65, 72, 73,88, 117, 137, 143, 199, and 210; C. I. Disperse Violet 43; C. I.Disperse Blue 96; C. I. Fluorescent Brightening Agent 112, 135, and 163;C. I. Solvent Orange 2 and 45; C. I. Solvent Red 1, 3, 8, 23, 24, 25,27, and 49; C. I. Pigment Green 10; and C. I. Pigment Brown 2. The lightabsorber is blended usually in a content of 10% by mass or less,preferably 5% by mass or less, based on the total mass of the solidcontent of the resist underlayer film material for lithography.

The rheology controlling agent is added for the purpose of mainlyenhancing the fluidity of the resist underlayer film formingcomposition, particularly enhancing the homogeneity of the filmthickness of the resist underlayer film or enhancing the fillingproperty of the resist underlayer film forming composition into theinside of a hole, in a baking process. Specific examples of the rheologycontrolling agent include: phthalic acid derivatives such as dimethylphthalate, diethyl phthalate, diisobutyl phthalate, dihexyl phthalate,and butylisodecyl phthalate; adipic acid derivatives such as di-n-butyladipate, diisobutyl adipate, diisooctyl adipate, and octyldecyl adipate;maleic acid derivatives such as di-n-butyl maleate, diethyl maleate, anddinonyl maleate; oleic acid derivatives such as methyl oleate, butyloleate, and tetrahydrofurfuryl oleate; and stearic acid derivatives suchas n-butyl stearate and glyceryl stearate. These rheology controllingagents are blended in a content of usually less than 30% by mass, basedon the total mass of the solid content of the resist underlayer filmmaterial for lithography.

The adhesion assistant is added for the purpose of mainly enhancing theadhesion of the resist underlayer film forming composition and thesubstrate or the resist, particularly preventing the resist from beingpeeled during development. Specific examples of the adhesion assistantinclude: chlorosilanes such as trimethylchlorosilane,dimethylvinylchlorosilane, methyldiphenylchlorosilane, andchloromethyldimethylchlorosilane; alkoxysilanes such astrimethylmethoxysilane, dimethyldiethoxysilane, methyldimethoxysilane,dimethylvinylethoxysilane, diphenyldimethoxysilane, andphenyltriethoxysilane; silazanes such as hexamethyldisilazane,N,N′-bis(trimethlsilyl)urea, dimethyltrimethylsilylamine, andtrimethylsilylimidazol; silanes such as vinyltrichlorosilane,γ-chloropropyltrimethoxysilane, γ-aminopropyltriethoxysilane, andγ-glycidoxypropyltrimethoxysilane; heterocyclic compounds such asbenzotriazole, benzimidazole, indazole, imidazole,2-mercaptobenzimidazole, 2-mercaptobenzothiazole,2-mercaptobenzooxazole, urazole, thiouracil, mercaptoimidazole, andmercaptopyrimidine; and urea or thiourea compounds such as1,1-dimethylurea and1,3-dimethylurea. These adhesion assistants areblended in a content of usually less than 5% by mass, preferably lessthan 2% by mass, based on the total mass of the solid content of theresist underlayer film material for lithography.

In the resist underlayer film material for lithography of the presentinvention, for causing no pinhole and no striation and further,enhancing the applicability relative to a surface unevenness, asurfactant can be blended. Examples of the surfactant include: nonionicsurfactants, for example polyoxyethylene alkyl ethers such aspolyoxyethylene lauryl ether, polyoxyethylene stearyl ether,polyoxyethylene cetyl ether, and polyoxyethylene oleyl ether,polyoxyethylene alkylallyl ethers such as polyoxyethylene octylphenolether and polyoxyethylene nonylphenol ether,polyoxyethylene-polyoxypropylene block copolymers, sorbitan fatty acidesters such as sorbitan monolaurate, sorbitan monopalmitate, sorbitanmonostearate, sorbitan monooleate, sorbitan trioleate, and sorbitantristearate, polyoxyethylene sorbitan fatty acid esters such aspolyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitanmonopalmitate, polyoxyethylene sorbitan monostearate, polyoxyethylenesorbitan trioleate, and polyoxyethylene sorbitan tristearate;fluorine-based surfactants, for example, EFTOP EF301, EF303, and EF352(trade names, manufactured by Tohkem Products Co., Ltd.), MEGAFAC F171,F173, and R-30 (trade names, manufactured by DIC Corporation), FluoradFC430 and FC431 (trade names, manufactured by Sumitomo 3M Limited),Asahi Guard AG710 and Surfron S-382, SC101, SC102, SC103, SC104, SC105,and SC106 (trade names, manufactured by Asahi Glass Co., Ltd.); andOrganosiloxane polymer KP341 (manufactured by Shin-Etsu Chemical Co.,Ltd.). The blending amount of the surfactant is usually 2.0% by mass orless, preferably 1.0% by mass or less, based on the total mass of thesolid content of the resist underlayer film material for lithography ofthe present invention. These surfactants may be used individually or incombination of two or more of them.

In the present invention, examples of the solvent for dissolving thepolymer, the crosslinking agent component, the crosslinking catalyst,and the like include ethylene glycol monomethyl ether, ethylene glycolmonoethyl ether, methylcellosolve acetate, ethylcellosolve acetate,diethylene glycol monomethyl ether, diethylene glycol monoethyl ether,propylene glycol, propylene glycol monomethyl ether, propylene glycolmonomethyl ether acetate, propylene glycol monoethyl ether, propyleneglycol monoethyl ether acetate, propylene glycol propyl ether acetate,toluene, xylene, methyl ethyl ketone, cyclopentanone, cyclohexanone,ethyl 2-hydroxypropionate, ethyl 2-hydroxy-2-methylpropionate, ethylethoxyacetate, ethyl hydroxyacetate, methyl 2-hydroxy-3-methylbutanate,methyl 3-methoxypropionate, ethyl 3-methoxypropionate, ethyl3-ethoxypropionate, methyl 3-ethoxypropionate, methyl pyruvate, ethylpyruvate, ethyl acetate, butyl acetate, ethyl lactate, and butyllactate. These organic solvents may be used individually or incombination of two or more of them.

Furthermore, to the solvent, a high boiling point-solvent such aspropylene glycol monobutyl ether and propylene glycol monobutyl etheracetate can be mixed to be used. Among these solvents, propylene glycolmonomethyl ether, propylene glycol monomethyl ether acetate, ethyllactate, butyl lactate, and cyclohexanone are preferred for enhancingthe leveling property.

As the resist used in the present invention, a photoresist, an electronbeam resist, and the like can be used.

As the photoresist applied and formed on the resist underlayer film forlithography in the present invention, both of a negative-typephotoresist and a positive-type photoresist can be used. Examples of thephotoresist include: a positive-type photoresist containing a novolacresin and 1,2-naphthoquinonediazide sulfonic acid ester; a chemicalamplification type photoresist containing a binder having a groupelevating alkali dissolving rate by being decomposed by an acid, and aphotoacid generator; a chemical amplification type photoresistcontaining an alkali-soluble binder, a low molecule compound elevatingalkali dissolving rate of a photoresist by being decomposed by an acid,and a photoacid generator; a chemical amplification type photoresistcontaining a binder having a group elevating alkali dissolving rate bybeing decomposed by an acid, a low molecule compound elevating alkalidissolving rate of a photoresist by being decomposed by an acid, and aphotoacid generator; and a photoresist having, in the skeleton thereof,an Si atom. Specific examples thereof include trade name: APEX-Emanufactured by Rohm and Haas Company.

Examples of the electron beam resist applied and formed on the resistunderlayer film for lithography in the present invention include: acomposition containing a resin containing a Si—Si bond in the backbonethereof and containing an aromatic ring at a terminal thereof, and anacid generator generating an acid by being irradiated with an electronbeam; or a composition containing poly(p-hydroxystyrene) in which ahydroxy group is substituted with an organic group containingN-carboxyamine and an acid generator generating an acid by beingirradiated with an electron beam. In the later electron beam resistcomposition, an acid generated from the acid generator by electron beamirradiation is reacted with an N-carboxyaminoxy group in a side chain ofthe polymer and the side chain of the polymer is decomposed to a hydroxygroup to exhibit alkali solubility and to be dissolved in an alkalinedeveloper, so that a resist pattern is formed. Examples of the acidgenerator generating an acid by the electron beam irradiation include: ahalogenated organic compound such as1,1-bis[p-chlorophenyl]-2,2,2-trichloroethane,1,1-bis[p-methoxyphenyl]-2,2,2-trichloroethane,1,1-bis[p-chlorophenyl]-2,2-dichloroethane, and2-chloro-6-(trichloromethyl)pyridine; an onium salt such as atriphenylsulfonium salt and a diphenyliodonium salt; and a sulfonic acidester such as nitrobenzyl tosylate and dinitrobenzyl tosylate.

Examples of the developer for the resist having the resist underlayerfilm formed using the resist underlayer film material for lithography ofthe present invention include aqueous solutions of alkalis such as:inorganic alkalis such as sodium hydroxide, potassium hydroxide, sodiumcarbonate, sodium silicate, sodium metasilicate, and ammonia water;primary amines such as ethylamine and n-propylamine; secondary aminessuch as diethylamine and di-n-butylamine; tertiary amines such astriethylamine and methyldiethylamine; alcoholamines such asdimethylethanolamine and triethanolamine; quaternary ammonium salts suchas tetramethylammonium hydroxide, tetraethylammonium hydroxide, andcholine; and cyclic amines such as pyrrole and piperidine. Furthermore,to the aqueous solution of the above alkalis, an appropriate amount ofalcohols such as isopropyl alcohol or a nonion-based or the likesurfactant may be added to be used. Among them, a preferred developer isa quaternary ammonium salt and further preferred developers aretetramethylammonium hydroxide and choline.

Next, the forming method of the resist pattern of the present inventionis described. Onto a substrate (for example, a transparent substratesuch as a glass substrate and an ITO substrate which are coated withsilicon/silicon dioxide) used for the production of a precise integratedcircuit element, a resist underlayer film forming composition is appliedby an appropriate coating method such as spinner and coater, and isbaked to be cured to produce a coating-type underlayer film. The resistunderlayer film has a film thickness of preferably 0.01 to 3.0 μm. Theconditions for baking after coating are at 80 to 350° C. and for 0.5 to120 minutes. Then, onto the resist underlayer film, either directly orif necessary, through a film formed with one layer or several layers ofa coating material on the coating-type underlayer film, the resist isapplied and the resist is irradiated with light or an electron beamthrough a predetermined mask. Then, by developing, rinsing, and dryingthe resist, an advantageous resist pattern can be obtained. Ifnecessary, heating after irradiation with light or an electron beam(PEB: Post Exposure Bake) can be performed. Then, by removing the resistunderlayer film in a part at which the resist is removed by developmentin the above process by dry etching, a desired pattern can be formed onthe substrate.

The exposure light for the photoresist is a chemical ray such as a nearultraviolet ray, a far ultraviolet ray, or an extreme ultraviolet ray(for example, EUV) and as the exposure light, light of a wavelength of248 nm (KrF laser light), 193 nm (ArF laser light), or 157 nm (F₂ laserlight) is used. The light irradiating method is not particularly limitedto be used as long as the method is a method capable of generating anacid from the photoacid generator and the light irradiating method isperformed with an exposure dose of 1 to 2,000 mJ/cm², 10 to 1,500mJ/cm², or 50 to 1,000 mJ/cm².

The electron beam irradiation for the electron beam resist can beperformed, for example, using an electron beam irradiating apparatus.

In the present invention, a semiconductor device can be produced througha process of forming a resist underlayer film with a resist underlayerfilm forming composition on a semiconductor substrate, a process offorming a resist film on the resist underlayer film, a process offorming a resist pattern by light irradiation or electron beamirradiation and development, a process of etching the resist underlayerfilm according to the resist pattern, and a process of processing thesemiconductor substrate according to the patterned resist underlayerfilm.

Progress in refinement of the resist pattern will cause a problem of theresolution or collapse of a resist pattern after development; therefore,thinning of the resist will be required. In this sense, it is difficultto secure a film thickness of the resist pattern sufficient forprocessing the substrate, which requires a process for imparting afunction as a mask for processing the substrate not only to the resistpattern, but also to the resist underlayer film provided between theresist and the semiconductor substrate to be processed. As a resistunderlayer film for such a process, there has started to be required aresist underlayer film for lithography having a selection ratio of a dryetching rate close to that of the resist, a resist underlayer film forlithography having a selection ratio of a dry etching rate smaller thanthat of the resist, and a resist underlayer film for lithography havinga selection ratio of a dry etching rate smaller than that of thesemiconductor substrate, as a resist underlayer film, unlike aconventional resist underlayer film having high etching rate property.In addition, to such a resist underlayer film, reflection preventingability can also be imparted, so that such a resist underlayer film canprovide a function of a conventional anti-reflective coating incombination with other advantageous properties.

For obtaining a fine resist pattern, there has started to be used also aprocess of making the resist pattern and the resist underlayer filmthinner than the pattern width during development of the resist, duringdry etching of the resist underlayer film. As a resist underlayer filmfor such a process, there has started to be required a resist underlayerfilm having a selection ratio of a dry etching rate close to that of theresist, unlike a conventional high etching rate anti-reflective coating.To such a resist underlayer film, a reflection preventing ability can beimparted, so that such a resist underlayer film can provide a functionof a conventional anti-reflective coating in combination with otheradvantageous properties.

In the present invention, the resist underlayer film of the presentinvention is formed on a substrate, and then on the resist underlayerfilm, either directly or if necessary, through a film formed with onelayer or several layers of coating material on the resist underlayerfilm, the resist can be applied. This makes it possible to process thesubstrate by selecting an appropriate etching gas even when the patternwidth of the resist is small and the resist is coated in a smallthickness for preventing a pattern collapse.

That is, through: a process of forming the resist underlayer film with aresist underlayer film forming composition on a semiconductor substrate;a process of forming a hardmask with a coating material containing asilicon component or the like on the resist underlayer film; a processof forming a resist film further on the hardmask; a process of forming aresist pattern by irradiation with light or an electron beam anddevelopment; a process of etching the hardmask according to the resistpattern; a process of etching the resist underlayer film according tothe patterned hardmask; and a process of processing the semiconductorsubstrate according to the patterned resist underlayer film, asemiconductor device can be produced.

In the resist underlayer film forming composition for lithography of thepresent invention, when the effect thereof as an anti-reflective coatingis considered, a light absorbing moiety is incorporated into theskeleton, so that there is no substance diffused into the photoresistduring heating and drying of the composition. Furthermore the lightabsorbing moiety has satisfactorily high light absorbing performance;therefore, the composition has high effect of preventing reflectedlight.

The resist underlayer film forming composition for lithography of thepresent invention has high thermal stability, can prevent contaminationof an upper layer film of the resist underlayer film by a decomposedsubstance during baking the resist underlayer film, and can allow leewayin the temperature margin for the baking process.

Furthermore, the resist underlayer film material for lithography of thepresent invention can be used, depending on the process condition, as afilm having a function of preventing reflection of light and further, afunction of preventing an interaction between the substrate and thephotoresist or a function of preventing an adverse action of a materialused for the photoresist or a substance generated during light exposureof the photoresist against the substrate.

EXAMPLE Synthesis Example 1

Into a flask equipped with a stirrer, a reflux apparatus, and athermometer, 28.04 g of 9,9-bis(4-hydroxyphenyl)fluorene, 13.97 g of4,4′-difluorobenzophenone, 12.32 g of potassium carbonate, and 162.56 gof N-methyl-2-pyrrolidinone were charged. Then, the inside of the flaskwas purged with nitrogen and the flask was heated until the innertemperature thereof became 140° C., followed by effecting the reactionfor about 24 hours. The synthesized polymer was cooled down to roomtemperature and the reaction mixture was filtered for removing aprecipitate to recover the resultant reaction filtrate. The reactionfiltrate was mixed with about 10 mL of a mixture ofN-methyl-2-pyrrolidinone and 2 mol/L hydrochloric acid in a volume ratioof 90:10. Then, the resultant reaction filtrate was charged intomethanol to perform reprecipitation purification of the reactionfiltrate.

Furthermore, the resultant precipitate was washed with water andmethanol and was vacuum-dried at 85° C. for about one day to obtain apolyether used in the present invention. The obtained polymercorresponded to Formula (3-1). The obtained polymer having an etherstructure was subjected to GPC analysis and the polymer had a weightaverage molecular weight of 6,900 and a polydispersity Mw/Mn of 1.83 interms of standard polystyrene.

Synthesis Example 2

Into a 100 mL three-neck flask, 6.76 g of6,6′-(9H-fluorene-9,9-diyl)dinaphthalene-2-ole, 3.27 g of4,4′-difluorobenzophenone, 42.72 g of N-methyl-2-pyrrolidinone, and 2.49g of potassium carbonate were charged. Then, the inside of the flask waspurged with nitrogen and the flask was heated to 170° C., followed byeffecting the reaction for about 24 hours. Then, to the resultantreaction mixture, 0.65 g of 1-naphthol dissolved in 5.84 g ofN-methyl-2-pyrrolidinone was added and the resultant reaction mixturewas stirred further for 2 hours. After the completion of the reaction,the reaction mixture was diluted with 20 g of N-methyl-2-pyrrolidinoneand a precipitate was removed by filtration. The recovered filtrate wasdropped into a mixed solution of methanol/water/toluene (350 g/50 g/30g) to perform reprecipitation. The resultant precipitate was filteredunder reduced pressure and the filtered substance was dried underreduced pressure at 85° C. over one night. Then, 7.92 g of a polyetherwas obtained as a light skin color powder. The obtained polymercorresponded to Formula (3-2). By GPC, the obtained polymer had a weightaverage molecular weight Mw of 9,400 and a polydispersity Mw/Mn of 2.21that were measured in terms of polystyrene.

Synthesis Example 3

Into a 100 mL three-neck flask, 5.09 g of4-(4-fluorophenylethynyl)phenol, 45.84 g of N-methyl-2-pyrrolidinone,and 3.65 g of potassium carbonate were charged. Then, the inside of theflask was purged with nitrogen and the flask was heated to 170° C.,followed by effecting the reaction for about 24 hours. After thecompletion of the reaction, a precipitate was removed by filtration. Therecovered filtrate was dropped into 400 g of methanol to performreprecipitation. The resultant precipitate was filtered under reducedpressure and the filtered substance was dried under reduced pressure at85° C. over one night. Then, 5.12 g of a polyether was obtained as agreen color powder. The obtained polymer corresponded to Formula (3-3).By GPC, the obtained polymer had a weight average molecular weight Mw of51,000 and a polydispersity Mw/Mn of 5.47 that were measured in terms ofpolystyrene.

Synthesis Example 4

Into a 100 mL three-neck flask, 2.76 g ofp-(3,4-difluorophenylethynyl)phenol, 2.10 g of9,9-bis(4-hydroxyphenyl)fluorene, 27.57 g of N-methyl-2-pyrrolidinone,and 3.48 g of potassium carbonate were charged. Then, the inside of theflask was purged with nitrogen and the flask was heated to 150° C.,followed by effecting the reaction for about 6 hours. After thecompletion of the reaction, a precipitate was removed by filtration. Therecovered filtrate was dropped into a mixed solution of methanol/water(500 g/250 g) to perform reprecipitation. The resultant precipitate wasfiltered under reduced pressure and the filtered substance was driedunder reduced pressure at 85° C. over one night. Then, 3.70 g of apolyether was obtained as a skin color powder. The obtained polymercorresponded to Formula (3-4). By GPC, the obtained polymer had a weightaverage molecular weight Mw of 20,000 and a polydispersity Mw/Mn of 4.49that were measured in terms of polystyrene.

Synthesis Example 5

Into a 100 mL three-neck flask, 8.06 g of9,9-bis(4-hydroxyphenyl)fluorene, 4.81 g of 2,4-difluorobiphenyl, 32.35g of N-methyl-2-pyrrolidinone, and 6.99 g of potassium carbonate werecharged. Then, the inside of the flask was purged with nitrogen and theflask was heated to 170° C., followed by effecting the reaction forabout 24 hours. Then, to the resultant reaction mixture, 0.99 g of1-naphthol dissolved in 8.95 g of N-methyl-2-pyrrolidinone was added andthe resultant reaction mixture was stirred further for 2 hours. Afterthe completion of the reaction, a precipitate was removed by filtration.The recovered filtrate was dropped into a mixed solution ofmethanol/water (160 g/40 g) to perform reprecipitation. The resultantprecipitate was filtered under reduced pressure and the filteredsubstance was dried under reduced pressure at 85° C. over one night.Then, 5.90 g of a polyether was obtained as a skin color powder. Theobtained polymer corresponded to Formula (3-5). By GPC, the obtainedpolymer had a weight average molecular weight Mw of 1,000 and apolydispersity Mw/Mn of 1.21 that were measured in terms of polystyrene.

Synthesis Example 6

As one example of synthesis of a polymer having a polyether structure,into a flask equipped with a stirrer, a reflux apparatus, and athermometer, 32.02 g of 2,2-bis(4-hydroxyphenyl)propane, 25.97 g of4,4′-difluorobenzophenone, 21.30 g of potassium carbonate, and 237.76 gof N-methyl-2-pyrrolidinone were charged. Then, the inside of the flaskwas purged with nitrogen and the flask was heated until the innertemperature thereof became 140° C., followed by effecting the reactionfor about 24 hours. The synthesized polymer was cooled down to roomtemperature and the reaction mixture was filtered for removing aprecipitate to recover the resultant reaction filtrate. The reactionfiltrate was mixed with about 10 mL of a mixture ofN-methyl-2-pyrrolidinone and 2 mol/L hydrochloric acid in a volume ratioof 90:10. Then, the resultant reaction filtrate was charged into a mixedsolution of methanol/water (volume ratio=90/10) to performreprecipitation purification of the reaction filtrate.

Furthermore, the resultant precipitate was washed with water andmethanol and was vacuum-dried at 85° C. for about one day to obtain apolyether used in the present invention. The obtained polymercorresponded to Formula (3-6). The obtained polymer having an etherstructure was subjected to GPC analysis and the polymer had a weightaverage molecular weight of 7,600 and a polydispersity Mw/Mn of 1.96 interms of standard polystyrene.

Synthesis Example 7

As one example of synthesis of a polymer having a polyether structure,into a flask equipped with a stirrer, a reflux apparatus, and athermometer, 17.52 g of 9,9-bis(4-hydroxyphenyl)fluorene, 6.22 g of2,6-difluorobenzonitrile, 7.64 g of potassium carbonate, and 94.63 g ofN-methyl-2-pyrrolidinone were charged. Then, the inside of the flask waspurged with nitrogen and the flask was heated until the innertemperature thereof became 140° C., followed by effecting the reactionfor about 24 hours. The synthesized polymer was cooled down to roomtemperature and the reaction mixture was filtered for removing aprecipitate to recover the resultant reaction filtrate. The reactionfiltrate was mixed with about 10 mL of a mixture ofN-methyl-2-pyrrolidinone and 2 mol/L hydrochloric acid in a volume ratioof 90:10. Then, the resultant reaction filtrate was charged into amethanol solution to perform reprecipitation purification of thereaction filtrate.

Furthermore, the resultant precipitate was washed with water andmethanol and was vacuum-dried at 85° C. for about one day to obtain19.72 g of a polyether used in the present invention. The obtainedpolymer corresponded to Formula (3-7). The obtained polymer having anether structure was subjected to GPC analysis and the polymer had aweight average molecular weight of 15,000 and a polydispersity Mw/Mn of2.65 in terms of standard polystyrene.

Synthesis Example 8

As one example of synthesis of a polymer having a polyether structure,into a flask equipped with a stirrer, a reflux apparatus, and athermometer, 26.29 g of 9,9-bis(4-hydroxyphenyl)fluorene, 11.35 g of2,5-difluoronitrobenzene, 11.40 g of potassium carbonate, and 147.07 gof N-methyl-2-pyrrolidinone were charged. Then, the inside of the flaskwas purged with nitrogen and the flask was heated until the innertemperature thereof became 140° C., followed by effecting the reactionfor about 24 hours. The synthesized polymer was cooled down to roomtemperature and the reaction mixture was filtered for removing aprecipitate to recover the resultant reaction filtrate. The reactionfiltrate was mixed with about 10 mL of a mixture ofN-methyl-2-pyrrolidinone and 2 mol/L hydrochloric acid in a volume ratioof 90:10. Then, the resultant reaction filtrate was charged into amethanol solution to perform reprecipitation purification of thereaction filtrate.

Furthermore, the resultant precipitate was washed with water andmethanol and was vacuum-dried at 85° C. for about one day to obtain28.39 g of a polyether used in the present invention. The obtainedpolymer corresponded to Formula (3-8). The obtained polymer having anether structure was subjected to GPC analysis and the polymer had aweight average molecular weight of 4,400 and a polydispersity Mw/Mn of1.70 in terms of standard polystyrene.

Example 1

3 g of the resin obtained in Synthesis Example 1 was dissolved in 12 gof cyclohexanone to prepare a solution of a resist underlayer filmforming composition used for a lithography process by a multilayer film.

Example 2

3 g of the resin obtained in Synthesis Example 2 was dissolved in 12 gof cyclohexanone to prepare a solution of a resist underlayer filmforming composition used for a lithography process by a multilayer film.

Example 3

3 g of the resin obtained in Synthesis Example 3 was dissolved in 12 gof cyclohexanone to prepare a solution of a resist underlayer filmforming composition used for a lithography process by a multilayer film.

Example 4

3 g of the resin obtained in Synthesis Example 4 was dissolved in 12 gof cyclohexanone to prepare a solution of a resist underlayer filmforming composition used for a lithography process by a multilayer film.

Example 5

3 g of the polymer obtained in Synthesis Example 5 was dissolved in 12 gof cyclohexanone to prepare a solution of a resist underlayer filmforming composition used for a lithography process by a multilayer film.

Example 6

3 g of the polymer obtained in Synthesis Example 6 was dissolved in 12 gof cyclohexanone to prepare a solution of a resist underlayer filmforming composition used for a lithography process by a multilayer film.

Example 7

To 20 g of the resin obtained in Synthesis Example 1, 3.0 g of acrosslinking agent (manufactured by Japan Cytec Industries, Inc.,containing as a component, tetramethoxymethyl glycoluril, Formula (7-1))and 0.30 g of p-toluenesulfonic acid as a catalyst were mixed and theresultant mixture was dissolved in 88 g of cyclohexanone to prepare asolution of a resist underlayer film forming composition used for alithography process by a multilayer film.

Example 8

To 20 g of the resin obtained in Synthesis Example 2, 3.0 g of acrosslinking agent (manufactured by Japan Cytec Industries, Inc.,containing as a component, tetramethoxymethyl glycoluril, Formula(7-1)), 0.30 g of pyridinium p-toluenesulfonate as a catalyst, and 0.06g of MEGAFAC R-30 as a surfactant were mixed and the resultant mixturewas dissolved in 88 g of cyclohexanone to prepare a solution of a resistunderlayer film forming composition used for a lithography process by amultilayer film.

Comparative Example 1

A solution of a cresol novolac resin (commercial product, weight averagemolecular weight: 4,000) was used.

Example 9

3 g of the polymer obtained in Synthesis Example 7 was dissolved in 12 gof cyclohexanone to prepare a solution of a resist underlayer filmforming composition used for a lithography process by a multilayer film.

Example 10

3 g of the polymer obtained in Synthesis Example 8 was dissolved in 12 gof cyclohexanone to prepare a solution of a resist underlayer filmforming composition used for a lithography process by a multilayer film.

Comparative Example 2

3 g of polyethylene glycol (manufactured by Tokyo Chemical Industry Co.,Ltd.) having a molecular weight of 1,000 was dissolved in 12 g ofpropylene glycol monoethyl ether acetate to prepare a solution.

(Measurement of Optical Parameters)

The resist underlayer film solutions prepared in Examples 1 to 10 andComparative Examples 1 and 2 were individually applied onto a siliconwafer with a spin coater. The solution was baked on a hot plate at 240°C. for 1 minute (in Comparative Example 1: at 205° C. for 1 minute, inComparative Example 2: at 160° C. for 1 minute) or at 400° C. for 2minutes to form a resist underlayer film (film thickness: 0.05 μm). Therefractive index (n value) at a wavelength of 193 nm and opticalabsorptivity (k value, also called attenuation coefficient) of theseresist underlayer films were measured using a spectroscopicellipsometer. The results of the measurements are listed in Table 1.

TABLE 1 Refractive index n and optical absorptivity k n k (193 nm) (193nm) Example 1 Film baked at 240° C. 1.48 0.77 Film baked at 400° C. 1.480.75 Example 2 Film baked at 240° C. 1.39 0.49 Film baked at 400° C.1.39 0.51 Example 3 Film baked at 240° C. 1.55 0.59 Film baked at 400°C. 1.54 0.63 Example 4 Film baked at 240° C. 1.49 0.64 Film baked at400° C. 1.63 0.73 Example 5 Film baked at 240° C. 1.47 0.77 Film bakedat 400° C. 1.46 0.73 Example 6 Film baked at 240° C. 1.58 0.81 Filmbaked at 400° C. 1.57 0.79 Example 7 Film baked at 240° C. 1.49 0.72Film baked at 400° C. 1.47 0.73 Example 8 Film baked at 240° C. 1.430.49 Film baked at 400° C. 1.40 0.51 Example 9 Film baked at 240° C.1.43 0.71 Film baked at 400° C. 1.41 0.70 Example 10 Film baked at 240°C. 1.47 0.75 Film baked at 400° C. 1.46 0.74 Comparative Film baked at205° C. 1.53 0.42 Example 1 Film baked at 400° C. UnmeasurableUnmeasurable Comparative Film baked at 160° C. 1.68 0.00 Example 2 Filmbaked at 400° C. Unmeasurable Unmeasurable

(Dissolution Test into Photoresist Solvents)

The solutions of the resist underlayer film forming composition preparedin Examples 1 to 10 were individually applied onto a silicon wafer witha spin coater. The solution was baked on a hot plate at 240° C. for 1minute (in Comparative Example 1: at 205° C. for 1 minute, inComparative Example 2: at 160° C. for 1 minute) or at 400° C. for 2minutes to form a resist underlayer film (film thickness: 0.20 μm). Theresist underlayer film was subjected to an immersion test in a solventused for the resist such as ethyl lactate, propylene glycol monomethylether, propylene glycol monomethyl ether acetate, and cyclohexanone.

Although the films prepared by baking the solutions of Examples 1 to 6and Examples 9 and 10 at 240° C. for 1 minute were dissolved in thesesolvents, it was confirmed that the films prepared by baking thesolutions of these Examples at 400° C. for 2 minutes were insoluble inthese solvents. In addition, it was also confirmed that not only thefilms prepared by baking the solutions of Examples 7 and 8 at 400° C.for 2 minutes, but also the films prepared by baking the solutions ofExamples 7 and 8 at 240° C. for 1 minute were insoluble in thesesolvents.

(Measurement of Dry Etching Rates)

The etcher and the etching gas used for the measurement of dry etchingrates were as follows.

-   RIE-10NR (manufactured by Samco, Inc.): CF₄

The solutions of the resist underlayer film forming composition preparedin Examples 1 to 10 and Comparative Examples 1 and 2 were individuallyapplied onto a silicon wafer with a spin coater. The solution was bakedon a hot plate at 240° C. for 1 minute (in Comparative Example 1: at205° C. for 1 minute, in Comparative Example 2: at 160° C. for 1 minute)or at 400° C. for 2 minutes to form a resist underlayer film (filmthickness: 0.20 μm). Using CF₄ gas as an etching gas, dry etching ratesof the resist underlayer films were measured.

In the same manner, a phenol novolac resin solution was applied onto asilicon wafer with a spin coater to form a coating film. Using CF₄ gasas an etching gas, the dry etching rate of the coating film was measuredand was compared with the dry etching rate of the resist underlayerfilms of Examples 1 to 10 and Comparative Examples 1 and 2. The resultsthereof are listed in Table 2. In Examples 1 to 10, the dry etching rateratio is a dry etching rate ratio (1) of (resist underlayer film bakedat 240° C.)/(phenol novolac resin baked at 240° C.) and a dry etchingrate ratio (2) of (resist underlayer film baked at 400° C.)/(phenolnovolac resin baked at 240° C.).

In Comparative Example 1, the dry etching rate ratio is a dry etchingrate ratio (1) of (resist underlayer film baked at 205° C.)/(phenolnovolac resin baked at 240° C.) and a dry etching rate ratio (2) of(resist underlayer film baked at 400° C.)/(phenol novolac resin baked at240° C.).

In Comparative Example 2, the dry etching rate ratio is a dry etchingrate ratio (1) of (resist underlayer film baked at 160° C.)/(phenolnovolac resin baked at 240° C.) and a dry etching rate ratio (2) of(resist underlayer film baked at 400° C.)/(phenol novolac resin baked at240° C.).

TABLE 2 Dry etching rate ratios Example 1 Dry etching rate ratio (1)0.84 Dry etching rate ratio (2) 0.84 Example 2 Dry etching rate ratio(1) 0.79 Dry etching rate ratio (2) 0.79 Example 3 Dry etching rateratio (1) 0.95 Dry etching rate ratio (2) 0.95 Example 4 Dry etchingrate ratio (1) 0.91 Dry etching rate ratio (2) 0.98 Example 5 Dryetching rate ratio (1) 0.86 Dry etching rate ratio (2) 0.85 Example 6Dry etching rate ratio (1) 0.96 Dry etching rate ratio (2) 0.96 Example7 Dry etching rate ratio (1) 0.86 Dry etching rate ratio (2) 0.85Example 8 Dry etching rate ratio (1) 0.82 Dry etching rate ratio (2)0.80 Example 9 Dry etching rate ratio (1) 0.82 Dry etching rate ratio(2) 0.81 Example 10 Dry etching rate ratio (1) 0.85 Dry etching rateratio (2) 0.84 Comparative Dry etching rate ratio (1) 1.00 Example 1 Dryetching rate ratio (2) Unmeasurable Comparative Dry etching rate ratio(1) 2.18 Example 2 Dry etching rate ratio (2) Unmeasurable

(Heat Resistance Test of Films)

The solutions of the resist underlayer film forming composition preparedin Examples 1 to 10 and Comparative Examples 1 and 2 were individuallyapplied onto a silicon wafer with a spin coater. The solution was bakedon a hot plate at 400° C. for 2 minutes to form a resist underlayer film(film thickness: 0.20 μm). The obtained film was heated with a rate of10° C./min and was subjected to thermogravimetric analysis in theatmosphere to measure a temperature at which the mass of the filmdecreased by 5%. The results thereof are listed in Table 3.

TABLE 3 Temperature at which mass of the film decreased by 5% Film bakedat 400° C. for 2 minutes Example 1 496° C. Example 2 500° C. Example 3452° C. Example 4 369° C. Example 5 395° C. Example 6 481° C. Example 7482° C. Example 8 472° C. Example 9 500° C. or more Example 10 408° C.Comparative Unmeasurable (when baked at 400° C., the Example 1 film wassublimated) Comparative Unmeasurable (when baked at 400° C., the Example2 film was sublimated)

INDUSTRIAL APPLICABILITY

The resist underlayer film material of the present invention used for alithography process by a multilayer film can provide a resist underlayerfilm having a selection ratio of a dry etching rate close to or smallerthan that of a photoresist and a selection ratio of a dry etching ratesmaller than that of a semiconductor substrate and further, can providean effect as an anti-reflective coating in combination with otheradvantageous properties unlike a conventional anti-reflective coatinghaving high etching rate property. In addition, it became apparent thatthe underlayer film material of the present invention has such heatresistance that allows a hardmask to be formed on the underlayer film asan upper layer of the underlayer film by vapor deposition.

1. A resist underlayer film forming composition for lithography,comprising: a polymer containing a unit structure of Formula (1):O—Ar₁  Formula (1) (in Formula (1), Ar₁ is a C₆₋₅₀ arylene group or anorganic group containing a heterocyclic group), a unit structure ofFormula (2):O—Ar₂—O—Ar₃-T-Ar₄  Formula (2) (in Formula (2), Ar₂, Ar₃, and Ar₄ areindividually a C₆₋₅₀ arylene group or an organic group containing aheterocyclic group; and T is a carbonyl group or a sulfonyl group), or acombination of the unit structure of Formula (1) and the unit structureof Formula (2).
 2. The resist underlayer film forming compositionaccording to claim 1, wherein the resist underlayer film formingcomposition for lithography contains a polymer containing the unitstructure of Formula (1), and the organic group of Ar₁ is an organicgroup containing a fluorene structure.
 3. The resist underlayer filmforming composition according to claim 1, wherein the resist underlayerfilm forming composition for lithography contains a polymer containingthe unit structure of Formula (2), and the organic group of Ar₂ is anorganic group containing a fluorene structure.
 4. The resist underlayerfilm forming composition according to claim 1, wherein the resistunderlayer film forming composition for lithography contains a polymercontaining a combination of the unit structure of Formula (1) and theunit structure of Formula (2), and at least one of the organic group ofAr₁ and the organic group of Ar₂ is an organic group containing afluorene structure.
 5. The resist underlayer film forming compositionaccording to claim 1, wherein the resist underlayer film formingcomposition for lithography contains a polymer containing the unitstructure of Formula (1), and the organic group of Ar₁ is an organicgroup containing a combination of an arylene group with a groupcontaining a carbon-carbon triple bond and/or a group containing acarbon-carbon double bond.
 6. The resist underlayer film formingcomposition according to claim 1, wherein the resist underlayer filmforming composition for lithography contains a polymer containing theunit structure of Formula (2), and the organic group of Ar₂ is anorganic group containing a combination of an arylene group with a groupcontaining a carbon-carbon triple bond and/or a group containing acarbon-carbon double bond.
 7. The resist underlayer film formingcomposition according to claim 1, wherein the resist underlayer filmforming composition for lithography contains a polymer containing acombination of the unit structure of Formula (1) and the unit structureof Formula (2), and at least one of the organic group of Ar₁ and theorganic group of Ar₂ is an organic group containing a combination of anarylene group with a group containing a carbon-carbon triple bond and/ora group containing a carbon-carbon double bond.
 8. The resist underlayerfilm forming composition according to claim 1, wherein the resistunderlayer film forming composition for lithography contains a polymercontaining the unit structure of Formula (1), and the organic group ofAr₁ is an organic group containing a biphenylene structure.
 9. Theresist underlayer film forming composition according to claim 1, whereinthe resist underlayer film forming composition for lithography containsa polymer containing the unit structure of Formula (2), and the organicgroup of Ar₂ is an organic group containing a biphenylene structure. 10.The resist underlayer film forming composition according to claim 1,wherein the resist underlayer film forming composition for lithographycontains a polymer containing a combination of the unit structure ofFormula (1) and the unit structure of Formula (2), and at least one ofthe organic group of Ar₁ and the organic group of Ar₂ is an organicgroup containing a biphenylene structure.
 11. The resist underlayer filmforming composition according to claim 1, wherein the resist underlayerfilm forming composition for lithography contains a polymer containingthe unit structure of Formula (2), and at least one of the organic groupof Ar₃ and the organic group of Ar₄ is a phenylene group.
 12. The resistunderlayer film forming composition according to claim 1, wherein theresist underlayer film forming composition for lithography contains apolymer containing a combination of the unit structure of Formula (1)and the unit structure of Formula (2), and at least one of the organicgroup of Ar₃ and the organic group of Ar₄ is a phenylene group.
 13. Theresist underlayer film forming composition according to claim 1, furthercomprising an acid or an acid generator.
 14. A resist underlayer filmobtained by applying the resist underlayer film forming composition asclaimed in claim 1 onto a semiconductor substrate and baking theresultant film.
 15. A method for producing a semiconductor device, themethod comprising: a process of forming an underlayer film with theresist underlayer film forming composition as claimed in claim 1 on asemiconductor substrate; a process of forming a resist film on theunderlayer film; a process of irradiating the resist film with light oran electron beam and developing the resist film so as to form a resistpattern; a process of etching the underlayer film according to theresist pattern of the resist film; and a process of processing thesemiconductor substrate according to the patterned underlayer film. 16.A method for producing a semiconductor device, the method comprising: aprocess of forming an underlayer film with the resist underlayer filmforming composition as claimed in claim 1 on a semiconductor substrate;a process of forming a hardmask on the underlayer film; a process offurther forming a resist film on the hardmask; a process of irradiatingthe resist film with light or an electron beam and developing the resistfilm so as to form a resist pattern; a process of etching the hardmaskaccording to the resist pattern of the resist film; a process of etchingthe underlayer film according to the patterned hardmask; and a processof processing the semiconductor substrate according to the patternedunderlayer film.